Method of locating thin inserts in elongated castings



Sept. 17, 1957 A. F. CRAVER METHOD OF LOCATING THIN INSERTS IN ELONGATED CASTINGS Filed July 18, 1955 'ArroRMs-y alto-6,272 METHODzOF-LOCATING THINNSERTS IN- ELONGATE'D 'CASTINGS Albert "Craver, Ba'y Village, fbhio, assig'mir to The Patrol valwcompanwclevelanu, Ohio, a corporation ammo Application July is, 19'5s,""seria1 No. 522,415 5 emails. (o1. zz 'zm Thisin'veritidil relate/81th metal ii'is'ert's embedded in castings. Particularly, it relates toa method of maintainiiig such inserts at tlfere quir'ed tension in the required position at the required temperature duriiig the casting operation to obtain "an improvedbondhetween a casting aniithe insert.

This invention also relates to an 'imbroveriiet iii the method and apparatus disclosed ilrpfltentapplication-6f AlbEftF. Cfiivr, Serial No. 423;900filed 1'9, 1954. The elesent embodiment "of the imiehtien relates "tocast mg light metal rods,.such as magnesium i'allo'y rods havinlg'a thin ferrous metal insert or core wire embedded therein. The inserts ma be made of various metals; having a hi'gher meltingpoint'thanthe Casting itself, and may 56 used ih both ferrous and "non-ferrous castings.

In making light metal castings of the type ailaove'described, =it was found that in sdhdeinstahcesthe iii'serfou: wire hetpropefly bonded to the castingaiifl thatsefiaration 'df-the twometa ls occurred. It is known that in' order to establish the proper contact between light metals such as aluminum or magnesium and heavier metals such as "iron Wire and the like, the heavier nietal should. be cleaned and preheated prior to the casting operation. Various means havebe'en used unsatisfactory from my viewpoint for fire'h'e ating the insert. These were found to be both timeconsuinirig im'firactical. I have discovered that satisfaetory preheating of the str' sed iiise'rt or Wire just 'pridnto castingfm'ayhe aceoirfqflishedi by applying 'eleotrieal current directly to the wire 'to bring it quickly tip to the desired temperature byelecflr'ical resistance of the wire itself. Thus the wire, lstressedi beyond its yield point at the temperaturebfthefmolterii castiiig metal; 'Will 0661 down simultaneously with: the: fre'eziiig of the molten metal ahout it, thereby firming a. proper bond between the wire and the casting,

For example, in the casting "0 f a :mag nesiiimalloy anode around a central "core wire, I have found that for an anode f approximately one inch outside diameter and; length of 36-i1'1che's, and core Wire of'ahout D1105 inch I insure that the "Iicessary core wire he centrally loc diameter, and when 20 pounds per square ihch air sure (gage) is applied 'to an air cylider 'havifig 'a4 'iri ch diameter piston that is joined to the core wire in the manner described in this application, the cio re wire Willi elongate at least inch when the hot {casting metal enters the mold and conir'nencesto surroundthe wire. I have found that during this,% inch elongation the wire is stressed beyond its yield point and that the wire does not return to its former length when the stress is removed and the Wire is cooled. The failure of the core wire, to return to its tanner length, is not caused by the bond formed between the core wire and "the anode, as proven by appropriate tests. 7 7

An object of my invention is ta-insure the creation of a proper bond between arelatively thin centrally located insert,-such as a ferrous metal wire, arid a easti'ng of non-ferrous metal, such for example as a magnesium alloy or aluminum alloycasting.

Another object of this invention is'to provide a inetllod employing electrical resistance heating means for quick ly preheating the insert or wire, to heat :it to ia'tem Patented Sept. 17, 1957 -2; perature liih er thanfthat of the mold just prior to the eastirigoperationysiieh means requiringtonly'a few-secends, lieingquicltly, and easily controlled and producingta castingliaifing the-insertproperly centered "and firmly 'ljonded to the casting;

Other objects are to proyide a, mold with a plurality of cavities, whichlis-aldapted-to simultaneously cast two o'rf'mdre elongatedt-bastiiigs-hayingjfl in metal inserts centrallydis'posd' ihreih,.suchmold being-provided at a relatively low 'cost, permitting relatively low unit'operatiiig costs, and Being "sturdy "and reliable in operation. Thes'eand othe'r obje ct s dfilie i liwirltio ll Will be apparent from the following specification.

In th'edrawings"diselosihg "ah illustrative emhodiment bl? fthe ih veiitiofi z n jFigg l isa side iiiw'of'iiiy 'iiiold'iim cllosed position; Big. 2 isaplan view t eh'dnit'he'liiies'pz of Fig. '1; Fig. 3is awfierticalse 'tibn "taken on'the line 3*3 o f Fig. :2; t t a Fig. "4i'sf'a bjrknen't'ral section through a basting fiiiiii d i'nftheil St rafd 'rii'cil'dj sihbwi ligthe celifl' al disjp osi ldn offthejmtaliiisrt'or'Wirefierein, while Fig 5 is a .x iew "of iah electrical 'swit'eh Eiittoh whieh c'bhtiolst lie flo'w "cuffent to'the device.

"Int geiiralffl'le I lioilihi iitdf the iiiiieritionh'fein dis clbfsed i'ijses a 'iwo j's'ec tiona-l 'hih'g'd tyi e irmarie rit irldld," dis p tiiiinincliiiedTbsition, inlndiii'g'alower fri'cil d portidnaitd a"siiriilari1ppr mold iiortion, adapted to be disposed-over the lower mold-pdr tioh'Huririgltlie castihg djg'iera tidn, each" 6111 in tirti'on ificludiiigitwo elona i cavities, the meld porti'o'ris 'heifig hingedtdgeth'er" iltilr theu'pineritioi-tia to be iiibv'e'd frdm a posi'tiont lr e' tlj oy the-1o er' 'i'aortion'to a josition 'at'thesiile therebfi spines "5 a'r'e oc'ateaat the topbtthe fold,"whileiarotatable" ooved sheavefinburited at the lowe eii'd bf the lower iindld p or'tio'n "below the cavities and he" gfits aids disposed 'atirilit angles to half round matingmoldcavities 15, illustrated in dotted lines in Figs. 1 and 2 and in full lines in Fig. 3. Hinge means 16 permit the upper mold portion 14 to be swung away from its position over the lower mold portion 13, as illustrated, to a position at the side thereof in a manner similar to moving a page of a book from a position over a page to a position at the side thereof. The opening and closing of the mold is accomplished by means of operating handle 27, while pneumatic clamping valve cylinders 17 operate the clamps 17a in an obvious manner, to clamp the two mold sections 13 and 14 together and release them. 7

Molten metal poured through sprue hole 18 at the top of the mold passes through connecting sprue hole leads 19 into the two elongated cavities 15, thus permitting the making of multiple castings from one pouring. A rotatable grooved sheave 20, as shown in Figs. 1 and 2, is mounted on the support beam 11 below the lower end of the mold 10 below the cavities, where it is positioned and arranged in such manner, that a wire insert 21 extending the length of said mold cavities and mounted around the sheave 20 is retained in each mold cavity 15 by merely securing one end of the wire 21 at the top of said mold10, placing it along one mold cavity 15 and then around the sheave 20 back into the adjacent mold cavity 15 and securing it at the top. The wire is centered within the mold cavity when sufficient tension is applied to the wire to make it taut.

As shown in Fig. 5 an electrical switch button 30, mounted on a panel 31 and disposed in close proximity to the mold 10, provides means for regulating the flow of current to the metal insert 21 as hereinafter described. As shown in Figs. 1 and 2, the sheave 20 is insulated from the mold 10 by a block of insulating material 32, while an electric conductor wire 33, suitably electrically connected to the sheave 20 at one end, is connected at its other end to a terminal connected to the switch button 30. The mold 10 is grounded by wire 34 as shown in Figs. 1 and 2. The switch button 30 is connected to a direct current line, preferably of 200 amp. 240 volts in such manner that whenever said button is pressed by the operator, current of the character above specified is caused to flow to the wire insert 21 and through the wire 21 to the mold 10, causing it to be quickly preheated. The lower ends of the insert 21 extend through apertures at the lower end of each half mold cavity and at initial preheating preferably do not touch the mold itself at that point, in order that the electric current passing to the sheave 20 is transmitted along the insert 21 to its upper end without being shorted out between these two points. If necessary, a block of insulating material may be provided in the mold adjacent the projecting insert ends to support them in alignment with the apertures without touching the mold structure. Preferably there should be a clearance of about 4: around the insert where it projects through the mold. When the mold sections 13 and 14 are closed, however, the weight of the top mold section 14 will force the wire insert 21 into proper position. A series of fuel burners 26 are disposed below the lower mold portion 13, which may be used to bring the mold 10 up to the proper temperature before starting a cast.

Means for gripping the upper ends of the insert wire 21 and stressing it comprise an air cylinder 22, controlled by a valve handle 28, having a piston 23 connected to a slidable base operating in ways 25a, while clamping fixtures 24 mounted on base 25 and provided with operating handles 2411 are adapted to clamp insert wire 21 disposed in horizontal bores therein. Compressed air at predetermined and controlled pressures, usually around 20 lb. per square inch is supplied to the piston 23*having a diameter of 4", and upon admitting such compressed air to the cylinder 22, clamping fixtures 24 will securely retain such wire ends at the required tension.

When using the mold 10, pneumatic clamp cylinders 17 operate clamp arms 17a, which are connected to the pistons 17b in cylinders 17 to release the two mold portions 13 and 14. When the two mold portions are released the operating handle 27 on upper mold portion 14 is grasped permitting the upper mold portion 14 to be swung on hinge means 16 to a position along the side of lower mold portion 13 with each mold cavity 15 facing upwardly. One end of wire 21 of predetermined length is inserted in the base of one clamping fixture 24 and handle 24a is operated to clamp it therein. The wire 21 is then strung through its adjacent mold cavity 15 and wound around the sheave 20 and strung back through the other mold cavity 15, and the other wire end is similarly clamped to the other clamping fixture 24. Operat ing handle 27 is then used to return upper mold portion 14 to its position over lower mold 13. The pneumatic clamping valves 17 then operate the clamping arms 17a to lock the upper mold portion 14 over the lower mold portion 13.

The rotatable sheave 20 serves to retain the wire insert 21 centrally in each of the two mold cavities 15 as shown in Figs. 2 and 3, and as such matching mold cavities are each of one-half round construction in cross-section, castings 29 which are round in cross-section are produced, each having the wire insert 21 disposed centrally thereof throughout the entire length, as shown in the completed casting in Fig. 4.

By operating valve handle 28, the air cylinder 22 is caused to carry the slidable base 25 and clamping fixtures 24 away from the end of the mold at a predetermined pressure, drawing the wire against the rotatable sheave 20, causing the wire 21 to become taut and centered in each mold cavity 15 at the desired tension. When the mold portions 13 and 14 are in their open positions, while the wire 21 is under tension, as above described, and

preceding the pouring of the metal, the operator presses the electric switch button 30 causing current of the character described to flow along the wire 21.

It has been found that by using electrical resistance pre-heating, the temperature of the wire insert is quickly brought up to a temperature substantially higher than the mean temperature of the mold. We have found that if the wire is heated to 600-750" F. sufiicient heat will remain in the wire insert during the interval between the closing of the mold and pouring of the metal to provide a satisfactory bond between the wire and the casting. The bond formed is thus stronger than that produced by not heating the wire to the above referred temperatures.

The time required for such heating of the wire 21 varies according to the type, length and diameter of wire used and to the magnitude of the applied voltage. If current is allowed to pass through the wire too long a time and it becomes overheated, the tension will cause the wire to break. In most instances, it has been found that passing current through the insert 21 for a period of time varying between 10 and 12 seconds is sut'ficient to bring a ferrous wire having a diameter within the range of .084 inch to .1055 inch, up to the proper temperature and permits excellent control of the process.

Quickly following the preheating of the insert, preferably within a period of a few seconds, the mold is closed, as described above, and while the insert is still at an elevated temperature, molten metal is poured into sprue hole 18 and flows through connecting sprue holes 19 into each of the two elongated mold cavities 15, filling them and forming a casting around the portions of the core wires within the cavities. Usually it is only necessary to leave the two mold portions closed for a minute or so, but if desired, the casting may remain in the molds for a longer period. Obviously the mold should not be opened until the molten metal has hardened somewhat at its surfaces and has at least begun to freeze around the insert. The core wire clamping fixtures 24 are then released and the clamping arms 17a are operated to release the two mold portions. The upper mold portion 14 is swung away from the lower mold portion 13. The ends of the wire 21 projecting beyond the lower mold end are cut and the two finished castings 29 are removed from the mold cavltres.

If desired more than a pair of castings may be formed at the same time and such construction is within the contemplated scope of this invention. It will be appreciated, however, that the method and apparatus herein disclosed may be used in casting other metals than those disclosed herein. By pouring suflicient molten metal to completely fill the cavities and the sprue hole 18 and the connecting sprue holes 19, a cast formation in the form of an inverted V is formed at the tops of the finished castings, which may be grasped for removing both castings 29 from the mold in a single operation.

It has been found that by using a rotatable sheave at one end of the mold, for retaining the wire centrally in the cavities, the pulling force or tension exerted by the slidable base 25 on the wire in each cavity is equalized. By preheating the wire by electrical resistance heating, a satisfactory mechanical bond between the wire and the magnesium is produced. The operation of the electric switch button 30 may be accomplished by the same operator who pours the molten metal.

It will be apparent to those skilled in the art that the present embodiment of the invention is illustrative only and that the invention may be variously changed, used or modified without departing from the spirit of the invention or sacrificing the advantages thereof.

I claim:

1. The method of locating a long thin metallic insert within the body of a light metal casting, said insert having a higher melting point than the light metal, said method comprising providing a long thin metallic insert of sufficient length to extend through the casting and protrude from opposite sides thereof, placing said insert in the mold with a portion of said insert passing through the mold cavity in said mold, gripping opposite ends of said insert, electrically preheating said insert within the mold cavity, introducing molten light metal into the mold cavity and casting said metal around said insert while providing a taut condition of the insert of such magnitude that the pre-heated insert is stressed beyond its yield point as its temperature rises through contact with the molten metal, releasing said tension after the molten metal has at least begun to freeze around the insert, and allowing the insert to cool down simultaneously with the freezing of the metal around the insert for firmly bonding the insert to the casting.

2. The method of locating a long thin metallic iron wire insert within and bonding such insert to the body of a magnesium base allow metal casting, said method comprising providing a long thin iron wire insert of suflicient length to extend through the casting and protrude from opposite sides thereof, placing said insert in a mold with a portion of said insert passing through the mold cavity in said mold, gripping opposite ends of said insert, pre-heating said insert, introducing molten metal of said magnesium base alloy into the mold cavity and casting said metal around said preheated insert, and while providing a taut condition of the insert of such magnitude that the insert is stressed beyond its yield point as its temperature rises through contact with the molten metal, releasing said tension after the molten metal has at least begun to freeze around the insert, and allowing the insert to cool down simultaneously with the freezing of the metal around the insert for firmly bonding the insert to the casting.

'3. The method of locating and firmly bonding a long thin metallic iron wire insert within the body of a magnesium base alloy casting, said method comprising providing a longthin iron wire insert of suific-ient length to extend through the casting and protrude from opposite sides thereof, placing said insert in the mold with a portion of said insert passing through the mold cavity in said mold, gripping opposite ends of said insert, preheating said insert within the mold cavity, to a temperature within the range of approximately 600 to 750 F., introducing molten metal of said base magnesium alloy into the mold cavity and around said insert and while said insert is still at an elevated temperature, and while providing a taut condition of the insert of such magnitude that the insert is stressed beyond its yield point and is elongated as its temperature rises through contact with the molten metal, releasing said tension after the molten metal has at least begun to freeze around the insert, and allowing the insert to cool down simultaneously with the freezing of the metal around the insert for firmly bonding the insert to the casting.

4. The method of locating a long thin metallic insert within the body of a light metal casting and firmly bonding said metal to said insert, said insert having a higher melting point than the light metal, said method comprising providing a thin metallic insert of sufficient length to extend through the casting and protrude from opposite sides thereof, placing said insert in the mold with a portion of said insert passing through the mold cavity in said mold, gripping opposite ends of said insert, applying tension to said insert exerting a pulling force beyond its yield strength when at the highest temperature to which it is exposed to produce a taut condition, preheating said insert in the mold cavity by electrical resistance heating to a temperature higher than the temperature of the mold, introducing molten light metal into the mold cavity and around said heated insert, maintaining the taut condition of the insert and measurably elongating the insert as its temperature rises through contact with the molten metal, and releasing said tension after the molten metal has at least begun to freeze around the insert, whereby when cooled, said metal is firmly bonded to said insert in its elongated condition.

5. The method of locating a longitudinally disposed iron wire insert within and firmly bonding the insert to a body of a rod-shaped magnesium base a-lloy casting, said method comprising providing an iron wire of sufficient length to extend through the casting and protrude from opposite ends thereof, placing said insert in the mold with a portion of said insert passing through and in concentric position with respect to the mold cavity in said mold, securing an end of the insert in fixed position and the other end in axially movable position and moving said second end a sufiicient distance to establish a predetermined tension in the insert greater than the yield strength of the insert at the maximum temperature to which said insert becomes heated by the molten metal being cast around the insert and by which tension said wire insert is firmly held in concentric position within the mold, substantially raising the temperature of said insert to a temperature within the range of approximately 600 to 750 F., while it is in said mold, then introducing molten metal of said magnesium base alloy into the mold cavity and casting it around said insert, while said insert is at an elevated temperature, maintaining the same tension of the insert as its temperature further rises through contact with the molten metal 'by causing further axial movement of said second end of said insert, and releasing said tension after the molten metal has at least begun to freeze around the insert, whereby when cooled said insert and said alloy casting are firmly bonded together.

References Cited in the file of this patent UNITED STATES PATENTS 951,753 Anderson Mar. 8, 1910 2,101,591 Muse Dec. 7, 1937 2,500,857 Norberg Mar. 14, 1950 2,515,191 Carpenter et al. July 18, 1950 2,552,810 ONeill et al. May 15, 1951 2,649,652 Duncan Aug. 25, 1953 

